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Iwata T, Yanagisawa T, Ikegaya Y, Smallwood J, Fukuma R, Oshino S, Tani N, Khoo HM, Kishima H. Hippocampal sharp-wave ripples correlate with periods of naturally occurring self-generated thoughts in humans. Nat Commun 2024; 15:4078. [PMID: 38778048 PMCID: PMC11111804 DOI: 10.1038/s41467-024-48367-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2023] [Accepted: 04/29/2024] [Indexed: 05/25/2024] Open
Abstract
Core features of human cognition highlight the importance of the capacity to focus on information distinct from events in the here and now, such as mind wandering. However, the brain mechanisms that underpin these self-generated states remain unclear. An emerging hypothesis is that self-generated states depend on the process of memory replay, which is linked to sharp-wave ripples (SWRs), which are transient high-frequency oscillations originating in the hippocampus. Local field potentials were recorded from the hippocampus of 10 patients with epilepsy for up to 15 days, and experience sampling was used to describe their association with ongoing thought patterns. The SWR rates were higher during extended periods of time when participants' ongoing thoughts were more vivid, less desirable, had more imaginable properties, and exhibited fewer correlations with an external task. These data suggest a role for SWR in the patterns of ongoing thoughts that humans experience in daily life.
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Affiliation(s)
- Takamitsu Iwata
- Department of Neurosurgery, Graduate School of Medicine, Osaka University, Osaka, 565-0871, Japan
| | - Takufumi Yanagisawa
- Department of Neurosurgery, Graduate School of Medicine, Osaka University, Osaka, 565-0871, Japan.
- Institute for Advanced Co-Creation Studies, Osaka University, Osaka, 565-0871, Japan.
| | - Yuji Ikegaya
- Laboratory of Chemical Pharmacology, Graduate School of Pharmaceutical Sciences, The University of Tokyo, Tokyo, 113-0033, Japan
- Institute for AI and Beyond, The University of Tokyo, Tokyo, 113-0033, Japan
- National Institute of Information and Communications Technology, Center for Information and Neural Networks, Suita City, Osaka, 565-0871, Japan
| | - Jonathan Smallwood
- Department of Psychology, Queen's University, Kingston, ON, K7L 3N6, Canada
| | - Ryohei Fukuma
- Department of Neurosurgery, Graduate School of Medicine, Osaka University, Osaka, 565-0871, Japan
- Institute for Advanced Co-Creation Studies, Osaka University, Osaka, 565-0871, Japan
| | - Satoru Oshino
- Department of Neurosurgery, Graduate School of Medicine, Osaka University, Osaka, 565-0871, Japan
| | - Naoki Tani
- Department of Neurosurgery, Graduate School of Medicine, Osaka University, Osaka, 565-0871, Japan
| | - Hui Ming Khoo
- Department of Neurosurgery, Graduate School of Medicine, Osaka University, Osaka, 565-0871, Japan
| | - Haruhiko Kishima
- Department of Neurosurgery, Graduate School of Medicine, Osaka University, Osaka, 565-0871, Japan
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Kucyi A, Anderson N, Bounyarith T, Braun D, Shareef-Trudeau L, Treves I, Braga RM, Hsieh PJ, Hung SM. Individual variability in neural representations of mind-wandering. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.01.20.576471. [PMID: 38328109 PMCID: PMC10849545 DOI: 10.1101/2024.01.20.576471] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/09/2024]
Abstract
Mind-wandering is a frequent, daily mental activity, experienced in unique ways in each person. Yet neuroimaging evidence relating mind-wandering to brain activity, for example in the default mode network (DMN), has relied on population-rather than individual-based inferences due to limited within-individual sampling. Here, three densely-sampled individuals each reported hundreds of mind-wandering episodes while undergoing multi-session functional magnetic resonance imaging. We found reliable associations between mind-wandering and DMN activation when estimating brain networks within individuals using precision functional mapping. However, the timing of spontaneous DMN activity relative to subjective reports, and the networks beyond DMN that were activated and deactivated during mind-wandering, were distinct across individuals. Connectome-based predictive modeling further revealed idiosyncratic, whole-brain functional connectivity patterns that consistently predicted mind-wandering within individuals but did not fully generalize across individuals. Predictive models of mind-wandering and attention that were derived from larger-scale neuroimaging datasets largely failed when applied to densely-sampled individuals, further highlighting the need for personalized models. Our work offers novel evidence for both conserved and variable neural representations of self-reported mind-wandering in different individuals. The previously-unrecognized inter-individual variations reported here underscore the broader scientific value and potential clinical utility of idiographic approaches to brain-experience associations.
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Wong YS, Yu J. Left superior parietal lobe mediates the link between spontaneous mind-wandering tendency and task-switching performance. Biol Psychol 2024; 185:108726. [PMID: 38036262 DOI: 10.1016/j.biopsycho.2023.108726] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2023] [Revised: 11/03/2023] [Accepted: 11/25/2023] [Indexed: 12/02/2023]
Abstract
While increasing studies have documented the link between mind wandering and task switching, less is known about which brain regions mediate this relationship. Using the MPI-Leipzig Mind-Brain-Body dataset (N = 173), we investigated the association between trait-level tendencies of mind wandering, task-switching performance, structural connectivity, and resting-state functional connectivity. At the behavioral level, we found that higher spontaneous mind-wandering trait scores were associated with shorter reaction times on both repeat and switch trials. The whole brain cortical thickness analysis revealed a strong mediating role of the left superior parietal lobe, which is part of the dorsal attention network, in the link between spontaneous mind-wandering tendency and task-switching performance. The resting-state functional connectivity analysis further demonstrated that this association was partly mediated by the negative dorsal attention network-default mode network functional connectivity. No significant mediating effects were found for deliberate mind-wandering tendency. Overall, the findings highlight the pivotal role of the left superior parietal lobe in activating new mental set during mind-wandering and task-switching processes, providing another evidence in favor of a role for switching in mind wandering.
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Affiliation(s)
- Yi-Sheng Wong
- Department of Psychology and Brain Health Research Centre, University of Otago, Dunedin, New Zealand; Science of Learning in Education Centre, Office of Education Research, National Institute of Education, Nanyang Technological University, Singapore.
| | - Junhong Yu
- Psychology, School of Social Sciences, Nanyang Technological University, Singapore
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Mallaroni P, Mason NL, Kloft L, Reckweg JT, van Oorsouw K, Toennes SW, Tolle HM, Amico E, Ramaekers JG. Shared functional connectome fingerprints following ritualistic ayahuasca intake. Neuroimage 2024; 285:120480. [PMID: 38061689 DOI: 10.1016/j.neuroimage.2023.120480] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2023] [Revised: 11/06/2023] [Accepted: 11/29/2023] [Indexed: 01/13/2024] Open
Abstract
The knowledge that brain functional connectomes are unique and reliable has enabled behaviourally relevant inferences at a subject level. However, whether such "fingerprints" persist under altered states of consciousness is unknown. Ayahuasca is a potent serotonergic psychedelic which produces a widespread dysregulation of functional connectivity. Used communally in religious ceremonies, its shared use may highlight relevant novel interactions between mental state and functional connectome (FC) idiosyncrasy. Using 7T fMRI, we assessed resting-state static and dynamic FCs for 21 Santo Daime members after collective ayahuasca intake in an acute, within-subject study. Here, connectome fingerprinting revealed FCs showed reduced idiosyncrasy, accompanied by a spatiotemporal reallocation of keypoint edges. Importantly, we show that interindividual differences in higher-order FC motifs are relevant to experiential phenotypes, given that they can predict perceptual drug effects. Collectively, our findings offer an example of how individualised connectivity markers can be used to trace a subject's FC across altered states of consciousness.
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Affiliation(s)
- Pablo Mallaroni
- Department of Neuropsychology and Psychopharmacology, Faculty of Psychology and Neuroscience, Maastricht University, P.O. Box 616, 6200 MD, Maastricht, the Netherlands.
| | - Natasha L Mason
- Department of Neuropsychology and Psychopharmacology, Faculty of Psychology and Neuroscience, Maastricht University, P.O. Box 616, 6200 MD, Maastricht, the Netherlands
| | - Lilian Kloft
- Department of Neuropsychology and Psychopharmacology, Faculty of Psychology and Neuroscience, Maastricht University, P.O. Box 616, 6200 MD, Maastricht, the Netherlands
| | - Johannes T Reckweg
- Department of Neuropsychology and Psychopharmacology, Faculty of Psychology and Neuroscience, Maastricht University, P.O. Box 616, 6200 MD, Maastricht, the Netherlands
| | - Kim van Oorsouw
- Department of Forensic Psychology, Faculty of Psychology and Neuroscience, Maastricht University, the Netherlands
| | - Stefan W Toennes
- Institute of Legal Medicine, University Hospital, Goethe University, Frankfurt/Main, Germany
| | | | | | - Johannes G Ramaekers
- Department of Neuropsychology and Psychopharmacology, Faculty of Psychology and Neuroscience, Maastricht University, P.O. Box 616, 6200 MD, Maastricht, the Netherlands
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5
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Rodolico A, Cutrufelli P, Brondino N, Caponnetto P, Catania G, Concerto C, Fusar-Poli L, Mineo L, Sturiale S, Signorelli MS, Petralia A. Mental Pain Correlates with Mind Wandering, Self-Reflection, and Insight in Individuals with Psychotic Disorders: A Cross-Sectional Study. Brain Sci 2023; 13:1557. [PMID: 38002517 PMCID: PMC10670292 DOI: 10.3390/brainsci13111557] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2023] [Revised: 10/29/2023] [Accepted: 11/05/2023] [Indexed: 11/26/2023] Open
Abstract
Understanding the cognitive processes that contribute to mental pain in individuals with psychotic disorders is important for refining therapeutic strategies and improving patient outcomes. This study investigated the potential relationship between mental pain, mind wandering, and self-reflection and insight in individuals diagnosed with psychotic disorders. We included individuals diagnosed with a 'schizophrenia spectrum disorder' according to DSM-5 criteria. Patients in the study were between 18 and 65 years old, clinically stable, and able to provide informed consent. A total of 34 participants, comprising 25 males and 9 females with an average age of 41.5 years (SD 11.5) were evaluated. The Psychache Scale (PAS), the Mind Wandering Deliberate and Spontaneous Scale (MWDS), and the Self-Reflection and Insight Scale (SRIS) were administered. Statistical analyses involved Spearman's rho correlations, controlled for potential confounders with partial correlations, and mediation and moderation analyses to understand the indirect effects of MWDS and SRIS on PAS and their potential interplay. Key findings revealed direct correlations between PAS and MWDS and inverse correlations between PAS and SRIS. The mediation effects on the relationship between the predictors and PAS ranged from 9.22% to 49.8%. The largest statistically significant mediation effect was observed with the SRIS-I subscale, suggesting that the self-reflection and insight component may play a role in the impact of mind wandering on mental pain. No evidence was found to suggest that any of the variables could function as relationship moderators for PAS. The results underscore the likely benefits of interventions aimed at reducing mind wandering and enhancing self-reflection in psychotic patients (e.g., metacognitive therapy, mindfulness). Further research will be essential to elucidate the underlying mechanisms.
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Affiliation(s)
- Alessandro Rodolico
- Psychiatry Unit, Department of Clinical and Experimental Medicine, University of Catania, Via Santa Sofia 78, 95123 Catania, Italy; (A.R.); (P.C.); (P.C.); (L.F.-P.); (L.M.); (M.S.S.); (A.P.)
| | - Pierfelice Cutrufelli
- Psychiatry Unit, Department of Clinical and Experimental Medicine, University of Catania, Via Santa Sofia 78, 95123 Catania, Italy; (A.R.); (P.C.); (P.C.); (L.F.-P.); (L.M.); (M.S.S.); (A.P.)
| | - Natascia Brondino
- Department of Brain and Behavioral Sciences, University of Pavia, Via Agostino Bassi 21, 27100 Pavia, Italy;
| | - Pasquale Caponnetto
- Psychiatry Unit, Department of Clinical and Experimental Medicine, University of Catania, Via Santa Sofia 78, 95123 Catania, Italy; (A.R.); (P.C.); (P.C.); (L.F.-P.); (L.M.); (M.S.S.); (A.P.)
- Department of Educational Sciences, Section of Psychology, University of Catania, Via Teatro Greco 84, 95124 Catania, Italy
| | | | - Carmen Concerto
- Psychiatry Unit, Department of Clinical and Experimental Medicine, University of Catania, Via Santa Sofia 78, 95123 Catania, Italy; (A.R.); (P.C.); (P.C.); (L.F.-P.); (L.M.); (M.S.S.); (A.P.)
| | - Laura Fusar-Poli
- Psychiatry Unit, Department of Clinical and Experimental Medicine, University of Catania, Via Santa Sofia 78, 95123 Catania, Italy; (A.R.); (P.C.); (P.C.); (L.F.-P.); (L.M.); (M.S.S.); (A.P.)
- Department of Brain and Behavioral Sciences, University of Pavia, Via Agostino Bassi 21, 27100 Pavia, Italy;
| | - Ludovico Mineo
- Psychiatry Unit, Department of Clinical and Experimental Medicine, University of Catania, Via Santa Sofia 78, 95123 Catania, Italy; (A.R.); (P.C.); (P.C.); (L.F.-P.); (L.M.); (M.S.S.); (A.P.)
| | - Serena Sturiale
- Psychiatry Unit, Department of Clinical and Experimental Medicine, University of Catania, Via Santa Sofia 78, 95123 Catania, Italy; (A.R.); (P.C.); (P.C.); (L.F.-P.); (L.M.); (M.S.S.); (A.P.)
| | - Maria Salvina Signorelli
- Psychiatry Unit, Department of Clinical and Experimental Medicine, University of Catania, Via Santa Sofia 78, 95123 Catania, Italy; (A.R.); (P.C.); (P.C.); (L.F.-P.); (L.M.); (M.S.S.); (A.P.)
| | - Antonino Petralia
- Psychiatry Unit, Department of Clinical and Experimental Medicine, University of Catania, Via Santa Sofia 78, 95123 Catania, Italy; (A.R.); (P.C.); (P.C.); (L.F.-P.); (L.M.); (M.S.S.); (A.P.)
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6
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Kucyi A, Kam JWY, Andrews-Hanna JR, Christoff K, Whitfield-Gabrieli S. Recent advances in the neuroscience of spontaneous and off-task thought: implications for mental health. NATURE MENTAL HEALTH 2023; 1:827-840. [PMID: 37974566 PMCID: PMC10653280 DOI: 10.1038/s44220-023-00133-w] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/27/2022] [Accepted: 08/25/2023] [Indexed: 11/19/2023]
Abstract
People spend a remarkable 30-50% of awake life thinking about something other than what they are currently doing. These experiences of being "off-task" can be described as spontaneous thought when mental dynamics are relatively flexible. Here we review recent neuroscience developments in this area and consider implications for mental wellbeing and illness. We provide updated overviews of the roles of the default mode network and large-scale network dynamics, and we discuss emerging candidate mechanisms involving hippocampal memory (sharp-wave ripples, replay) and neuromodulatory (noradrenergic and serotonergic) systems. We explore how distinct brain states can be associated with or give rise to adaptive and maladaptive forms of thought linked to distinguishable mental health outcomes. We conclude by outlining new directions in the neuroscience of spontaneous and off-task thought that may clarify mechanisms, lead to personalized biomarkers, and facilitate therapy developments toward the goals of better understanding and improving mental health.
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Affiliation(s)
- Aaron Kucyi
- Department of Psychological and Brain Sciences, Drexel University
| | - Julia W. Y. Kam
- Department of Psychology and Hotchkiss Brain Institute, University of Calgary
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7
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Llorens A, Bellier L, Blenkmann AO, Ivanovic J, Larsson PG, Lin JJ, Endestad T, Solbakk AK, Knight RT. Decision and response monitoring during working memory are sequentially represented in the human insula. iScience 2023; 26:107653. [PMID: 37674986 PMCID: PMC10477069 DOI: 10.1016/j.isci.2023.107653] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2022] [Revised: 06/05/2023] [Accepted: 07/11/2023] [Indexed: 09/08/2023] Open
Abstract
Emerging research supports a role of the insula in human cognition. Here, we used intracranial EEG to investigate the spatiotemporal dynamics in the insula during a verbal working memory (vWM) task. We found robust effects for theta, beta, and high frequency activity (HFA) during probe presentation requiring a decision. Theta band activity showed differential involvement across left and right insulae while sequential HFA modulations were observed along the anteroposterior axis. HFA in anterior insula tracked decision making and subsequent HFA was observed in posterior insula after the behavioral response. Our results provide electrophysiological evidence of engagement of different insula subregions in both decision-making and response monitoring during vWM and expand our knowledge of the role of the insula in complex human behavior.
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Affiliation(s)
- Anaïs Llorens
- Helen Wills Neuroscience Institute, University of California, Berkeley, Berkeley, CA, USA
- Université de Franche-Comté, SUPMICROTECH, CNRS, Institut FEMTO-ST, 25000 Besançon, France
- Université Paris Cité, Institute of Psychiatry and Neuroscience of Paris (IPNP), INSERM U1266, Team TURC, 75014 Paris, France
| | - Ludovic Bellier
- Helen Wills Neuroscience Institute, University of California, Berkeley, Berkeley, CA, USA
| | - Alejandro O. Blenkmann
- Department of Psychology, University of Oslo, Oslo, Norway
- RITMO Center for Interdisciplinary Studies in Rhythm, Time and Motion, University of Oslo, Oslo, Norway
| | | | - Pål G. Larsson
- Department of Neurosurgery, Oslo University Hospital, Oslo, Norway
| | - Jack J. Lin
- Department of Neurology and Center for Mind and Brain, University of California, Davis, Davis, CA, USA
| | - Tor Endestad
- Department of Psychology, University of Oslo, Oslo, Norway
- RITMO Center for Interdisciplinary Studies in Rhythm, Time and Motion, University of Oslo, Oslo, Norway
- Department of Neuropsychology, Helgeland Hospital, Mosjøen, Norway
| | - Anne-Kristin Solbakk
- Department of Neurosurgery, Oslo University Hospital, Oslo, Norway
- Department of Psychology, University of Oslo, Oslo, Norway
- RITMO Center for Interdisciplinary Studies in Rhythm, Time and Motion, University of Oslo, Oslo, Norway
- Department of Neuropsychology, Helgeland Hospital, Mosjøen, Norway
| | - Robert T. Knight
- Helen Wills Neuroscience Institute, University of California, Berkeley, Berkeley, CA, USA
- Department of Psychology, University of California, Berkeley, Berkeley, CA, USA
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8
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Tikka P, Kaipainen M, Salmi J. Narrative simulation of social experiences in naturalistic context - A neurocinematic approach. Neuropsychologia 2023; 188:108654. [PMID: 37507066 DOI: 10.1016/j.neuropsychologia.2023.108654] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2022] [Revised: 07/02/2023] [Accepted: 07/25/2023] [Indexed: 07/30/2023]
Abstract
Narratives may be regarded as simulations of everyday social situations. They are key to studying the human mind in socio-culturally determined contexts as they allow anchoring to the common ground of embodied and environmentally-engaged cognition. Here we review recent findings from naturalistic neuroscience on neural functions in conditions that mimic lifelike situations. We will focus particularly on neurocinematics, a research field that applies mediated narratives as stimuli for neuroimaging experiments. During the last two decades, this paradigm has contributed to an accumulation of insights about the neural underpinnings of behavior and sense-making in various narratively contextualized situations particularly pertaining to socio-emotional encounters. One of the key questions in neurocinematics is, how do intersubjectively synchronized brain activations relate to subjective experiences? Another question we address is how to bring natural contexts into experimental studies. Seeking to respond to both questions, we suggest neurocinematic studies to examine three manifestations of the same phenomenon side-by-side: subjective experiences of narrative situations, unfolding of narrative stimulus structure, and neural processes that co-constitute the experience. This approach facilitates identifying experientially meaningful activity patterns in the brain and points out what they may mean in relation to shared and communicable contents. Via rich-featured and temporally contextualized narrative stimuli, neurocinematics attempts to contribute to emerging holistic theories of neural dynamics and connectomics explaining typical and atypical interindividual variability.
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Affiliation(s)
- Pia Tikka
- Enactive Virtuality Lab, Baltic School of Film, Media and Arts, Tallinn University, Estonia.
| | | | - Juha Salmi
- Translational Cognitive Neuroscience Lab, Department of Neuroscience and Biomedical Engineering, Aalto University, Espoo, Finland
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Menon V. 20 years of the default mode network: A review and synthesis. Neuron 2023; 111:2469-2487. [PMID: 37167968 PMCID: PMC10524518 DOI: 10.1016/j.neuron.2023.04.023] [Citation(s) in RCA: 48] [Impact Index Per Article: 48.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2023] [Revised: 04/04/2023] [Accepted: 04/20/2023] [Indexed: 05/13/2023]
Abstract
The discovery of the default mode network (DMN) has revolutionized our understanding of the workings of the human brain. Here, I review developments that led to the discovery of the DMN, offer a personal reflection, and consider how our ideas of DMN function have evolved over the past two decades. I summarize literature examining the role of the DMN in self-reference, social cognition, episodic and autobiographical memory, language and semantic memory, and mind wandering. I identify unifying themes and propose new perspectives on the DMN's role in human cognition. I argue that the DMN integrates and broadcasts memory, language, and semantic representations to create a coherent "internal narrative" reflecting our individual experiences. This narrative is central to the construction of a sense of self, shapes how we perceive ourselves and interact with others, may have ontogenetic origins in self-directed speech during childhood, and forms a vital component of human consciousness.
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Affiliation(s)
- Vinod Menon
- Department of Psychiatry & Behavioral Sciences and Department of Neurology & Neurological Sciences, Wu Tsai Neurosciences Institute, Stanford University, Stanford, CA, USA.
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10
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Martínez-Pérez V, Andreu A, Sandoval-Lentisco A, Tortajada M, Palmero LB, Castillo A, Campoy G, Fuentes LJ. Vigilance decrement and mind-wandering in sustained attention tasks: Two sides of the same coin? Front Neurosci 2023; 17:1122406. [PMID: 37056308 PMCID: PMC10086236 DOI: 10.3389/fnins.2023.1122406] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2022] [Accepted: 03/10/2023] [Indexed: 03/30/2023] Open
Abstract
BackgroundDecrements in performance and the propensity for increased mind-wandering (i.e., task-unrelated thoughts) across time-on-task are two pervasive phenomena observed when people perform vigilance tasks. In the present study, we asked whether processes that lead to vigilance decrement and processes that foster the propensity for mind-wandering (MW) can be dissociated or whether they share a common mechanism. In one experiment, we introduced two critical manipulations: increasing task demands and applying anodal high-definition transcranial direct current stimulation (HD-tDCS) to the left dorsolateral prefrontal cortex.MethodSeventy-eight participants were randomly assigned to one of four groups resulting from the factorial combination of task demand (low, high) and stimulation (anodal, sham). Participants completed the sustained attention to response task (SART), which included thought probes on intentional and unintentional MW. In addition, we investigated the crucial role of alpha oscillations in a novel approach. By assessing pre-post resting EEG, we explored whether participants’ variability in baseline alpha power predicted performance in MW and vigilance decrement related to tDCS or task demands, respectively, and whether such variability was a stable characteristic of participants.ResultsOur results showed a double dissociation, such that task demands exclusively affected vigilance decrement, while anodal tDCS exclusively affected the rate of MW. Furthermore, the slope of the vigilance decrement function and MW rate (overall, intentional and unintentional) did not correlate. Critically, resting state alpha-band activity predicted tDCS-related gains in unintentional MW alone, but not in vigilance decrement, and remained stable after participants completed the task.ConclusionThese results show that when a sustained attention task involving executive vigilance, such as the SART, is designed to elicit both vigilance decrement effects and MW, the processes leading to vigilance decrement should be differentiated from those responsible for MW, a claim that is supported by the double dissociation observed here and the lack of correlation between the measures chosen to assess both phenomena. Furthermore, the results provide the first evidence of how individual differences in alpha power at baseline may be of crucial importance in predicting the effects of tDCS on MW propensity.
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11
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Silberstein RB, Pipingas A, Scholey AB. Homocysteine Modulates Brain Functional Connectivity in a Memory Retrieval Task. J Alzheimers Dis 2022; 90:199-209. [DOI: 10.3233/jad-220612] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Background: Homocysteine, a methionine metabolite, is a recognized risk factor for accelerated age-related cognitive decline and dementia. Objective: In the light of studies indicating increases in brain activity and brain functional connectivity in the early stages of age-related cognitive decline, we undertook a study to examine the relationship between plasma homocysteine levels and brain functional connectivity in a group of late middle-aged males at risk of cognitive decline due to high body mass index and a sedentary lifestyle. Methods: Brain functional connectivity was measured using the steady state visual evoked potential event related partial coherence while 38 participants performed a memory task where each trial comprised an object recognition task followed by a location memory task. Results: We observed a significant transient peak in the correlation between plasma homocysteine levels and fronto-parietal brain functional connectivity immediately before the presentation of the memory location component of the task. Significantly, this correlation was only apparent if the participant pool included individuals with homocysteine concentrations above 11μmole/L. Conclusion: Our findings suggest that the increased brain functional connectivity observed in the earlier stages of age-related cognitive decline reflects pathognomonic changes in brain function and not compensatory changes engaged to enhance task performance. Our findings also suggest that homocysteine interferes with the inhibition of cortical networks where this inhibition is necessary for optimum task performance. Finally, we observed that the effect of homocysteine on brain functional connectivity is only apparent at concentrations above 11μmol/L.
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Affiliation(s)
- Richard B. Silberstein
- Centre for Human Psychopharmacology, Swinburne University of Technology, Hawthorn, VIC, Australia
- Neuro-Insight Pty Ltd, Hawthorn, VIC, Australia
| | - Andrew Pipingas
- Centre for Human Psychopharmacology, Swinburne University of Technology, Hawthorn, VIC, Australia
| | - Andrew B. Scholey
- Centre for Human Psychopharmacology, Swinburne University of Technology, Hawthorn, VIC, Australia
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12
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Kam JWY, Rahnuma T, Park YE, Hart CM. Electrophysiological markers of mind wandering: A systematic review. Neuroimage 2022; 258:119372. [PMID: 35700946 DOI: 10.1016/j.neuroimage.2022.119372] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2021] [Revised: 06/08/2022] [Accepted: 06/10/2022] [Indexed: 10/18/2022] Open
Abstract
The ability to mentally wander away from the external environment is a remarkable feature of the human mind. Although recent years have witnessed a surge of interest in examining mind wandering using EEG, there is no comprehensive review that summarizes and accounts for the variable findings. Accordingly, we conducted a systematic review that synthesizes evidence from EEG studies that examined the electrophysiological measures of mind wandering. Our search yielded 42 studies that met eligibility criteria. The reviewed literature converges on a reduction in the amplitude of canonical ERP components (i.e., P1, N1 and P3) as the most reliable markers of mind wandering. Spectral findings were less robust, but point towards greater activity in lower frequency bands, (i.e., delta, theta, and alpha), as well as a decrease in beta band activity, during mind wandering compared to on-task states. The variability in these findings appears to be modulated by the task context. To integrate these findings, we propose an electrophysiological account of mind wandering that explains how the brain supports this inner experience. Conclusions drawn from this work will inform future endeavours in basic science to map out electrophysiological patterns underlying mind wandering and in translational science using EEG to predict the occurrence of this phenomenon.
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Affiliation(s)
- J W Y Kam
- Department of Psychology, University of Calgary. 2500 University Dr. NW., Calgary, AB, T2N 1N4, Canada; Hotchkiss Brain Institute, University of Calgary. 3330 Hospital Dr. NW., Calgary, AB, T2N 4N1, Canada.
| | - T Rahnuma
- Hotchkiss Brain Institute, University of Calgary. 3330 Hospital Dr. NW., Calgary, AB, T2N 4N1, Canada
| | - Y E Park
- Department of Psychology, University of Calgary. 2500 University Dr. NW., Calgary, AB, T2N 1N4, Canada
| | - C M Hart
- Department of Psychology, University of Calgary. 2500 University Dr. NW., Calgary, AB, T2N 1N4, Canada
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